ROME, Oct 5 (Reuters) - Italy's central bank wants the European Central Bank to soften new guidelines requiring lenders to set aside more capital to cover newly classified bad loans, a source close to the Bank of Italy said on Thursday.

Italian banks hold nearly 30 percent of the euro zone's 915 billion euros ($1.07 trillion) mountain of problematic debts, and investors are concerned the new ECB guidelines, announced on Wednesday, will lead to further writedowns of soured loans.

The source said the Bank of Italy wanted, at the very least, that secured loans be exempted from the new measures as well as the existing stock of bad loans, the source said.

The guidelines are to apply to loans newly classified as impaired from Jan. 1 next year, but Italy fears they could be extended to apply to all existing bad loans.

Italy's central bank hopes that a public consultation on the new proposals, which will run until Dec. 8, will lead to a balanced version of the new measures, the source said.($1 = 0.8541 euros) (Reporting by Stefano Bernabei, writing by Silvia Aloisi, editing by Mark Bendeich)